How to execute commands in gnuplot using shell script?

What I want to do is write a script which first launches a program and then tells it to execute a bunch of commands and then quit. Lets go with an example.

I wrote this script myscript.sh and it doesn't work the way I want it to. What it does is just run gnuplot and wait for it to quit and then runs the other commands; which obviously produces errors.

#!/bin/bash
gnuplot
plot sin(x)
pause -1
quit

I guess it is clear what I'm trying to do; if not, then let me know in the comments.

Solution 1:

One way is with -persist:

#!/usr/bin/gnuplot -persist
set title "Walt pedometer" font ",14" textcolor rgbcolor "royalblue"
set timefmt "%y/%m/%d"
set xdata time
set pointsize 1
set terminal wxt  enhanced title "Walt's steps " persist raise
plot "/home/walt/var/Pedometer" using 1:2 with linespoints

another way, if you need to preprocess data, is with a Bash Here Document (see man bash):

#!/bin/bash
minval=0    # the result of some (omitted) calculation
maxval=4219   # ditto
gnuplot -persist <<-EOFMarker
    set title "Walt pedometer" font ",14" textcolor rgbcolor "royalblue"
    set timefmt "%y/%m/%d"
    set yrange $minval:$maxval
    set xdata time
    set pointsize 1
    set terminal wxt  enhanced title "Walt's steps " persist raise
    plot "/home/walt/var/Pedometer" using 1:2 with linespoints
EOFMarker
# rest of script, after gnuplot exits

Solution 2:

From man gnuplot or its online manpage:

   -p,  --persist  lets  plot  windows  survive after main gnuplot program
   exits.

   -e "command list" executes the requested commands  before  loading  the
   next input file.

So what you probably want to run is the following command:

gnuplot -e "plot sin(x); pause -1"

Other variants I proposed but which are not that useful were:

gnuplot -p -e "plot sin(x); pause -1"
gnuplot -e "plot sin(x)"
gnuplot -p -e "plot sin(x)"

Solution 3:

As explained in the man pages, gnuplot expects input from a command file in what is called an batch session. You can e.g. write the line plot sin(x) to a file myplot and then execute gnuplot myplot.

If you omit the command file, as your script does, you will get an interactive session.

Solution 4:

This might help

{#set terminal postfile             
{#set output  "d1_plot.ps"        
set title "Energy vs. Time for Sample Data"    
set xlabel "Time"    
set ylabel "Energy"    
plot "d1.dat" with lines   
pause -1 "Hit Enter to continue"

click here for more details